The present invention relates to a silver salt photothermographic dry imaging material, and an image recording method and an image forming method by the use thereof.
Heretofore, in the medical and printing plate making fields, effluent resulting from wet type processing for image forming materials has become problematic in terms of workability. In recent years, from the viewpoint of environmental protection as well as space saving, a decrease in processing effluent has been highly demanded. Accordingly, there have been demanded techniques regarding photothermographic materials. These materials can be efficiently exposed utilizing laser imagers and image setters, and can form clear black-and-white images with a high resolution.
Examples of these techniques are described in U.S. Pat. Nos. 3,152,904 and 3,487,075, as well as in D. Morgan and B. Shely, xe2x80x9cThermally Processed Silver Systemsxe2x80x9d, (Image Processes and Materials, Neblette 8th edition, edited by Sturge, V. Walworth and A. Shepp, page 2, 1969). In these references have been disclosed silver salt photothermographic dry imaging materials that produce photographic images by employing a thermal development process.
These silver salt photothermographic dry imaging materials (hereafter it is also called xe2x80x9cphotothermographic imaging materialsxe2x80x9d) are characterized by a photosensitive layer that forms images by thermal development commonly at 80 to 140xc2x0 C. In the photosensitive layer, an organic silver salt is used as a source of silver ions by utilizing an incorporated reducing agent and photosensitive silver halide grains as a photo-sensor. This image forming process does not comprise a fixing process. Much effort has been directed toward improvement of shapes of organic silver salt particles that can be easily and properly allocated in a photosensitive layer and have less adverse influence by light scattering. These shapes are expected to supply silver ions with smooth progress to silver halides, and at the same time to prevent the resulting image from decreasing transparency by light scattering in said photosensitive layer.
For the above-mentioned objects, however, an attempt to simply make particles smaller in size by dispersion or cracking with high mechanical energy using a disperser, causes problems of raised fog and lowered sensitivity. Further, this results in deteriorated image quality. These problems occur as a result of damaging said silver halide particles and organic silver salt particles. Accordingly, techniques to obtain high sensitivity and high image density without increasing an amount of silver, and also lowering fog density, are required.
A silane coupling agent is generally employed to enhance the strength of FRP (fiber glass reinforced plastics). In recent years, it has been widely employed due to its effect of adhesive properties of boundary surfaces of inorganic materials and organic resins, and thus, it is well known that said silane coupling agents are employed as hardeners for silver salt photothermographic dry imaging materials, as described in U.S. Pat. Nos. 4,886,739, 5,264,334 and 5,294,526.
The inventors of the present invention, however, have found that specific silyl compounds show distinguished effects of yielding high maximum density, high sensitivity and lowered fog when employed in photothermographic imaging materials.
An object of the present invention is to provide a silver salt photothermographic dry imaging material that exhibits high maximum density and minimizes fog, and also to provide an image recording method and an image forming method, herein, both of which use said silver salt photothermographic dry imaging material.
The object of the invention can be achieved by the following embodiments.
1. A photothermographic imaging material comprising a support having thereon a photosensitive layer comprising a photosensitive silver halide, a light-insensitive organic silver salt, a binder and a reducing agent for silver ions,
wherein the photosensitive layer has a silver coverage of 0.8 to 2.5 g/m2, and the photosensitive layer comprises a compound represented by Formula (A) or Formula (B): 
wherein each R3, R4 and R5 is independently an alkyl group, an alkenyl group, an alkynyl group, an aryl group or a heterocyclic group, provided that R5 includes a group represented by Formula (xcex1): 
wherein Z represents OR2, X, or OH; n is an integer of 1 to 3; each R1 and R2 is independently an alkyl group, an alkenyl group, an alkynyl group, an aryl group or a heterocyclic group; and X is a chlorine atom or a bromine atom, 
wherein Z2 is OR22, X2, or OH; n2 is an integer of 1 to 3; each R21 and R22 is independently an alkyl group, an alkenyl group, an alkynyl group, an aryl group or a heterocyclic group, provided that R21 contains at least one primary amino group or at least two selected from the group consisting of primary and secondary amino groups; and X is a chlorine atom or a bromine atom.
2. The photothermographic imaging material of item 1,
wherein the photosensitive layer has a silver coverage of 0.8 to 1.6 g/m2.
3. A photothermographic imaging material comprising a support having thereon a photosensitive layer comprising a photosensitive silver halide, a light-insensitive organic silver salt, a binder and a reducing agent for silver ions,
wherein the photosensitive silver halide has an average particle size of 0.01 to 0.15 xcexcm, and the photosensitive layer comprises a compound represented by Formula (A) or Formula (B): 
wherein each R3, R4 and R5 is independently an alkyl group, an alkenyl group, an alkynyl group, an aryl group or a heterocyclic group, provided that R5 includes a group represented by Formula (xcex1): 
wherein Z is OR2, X, or OH; n is an integer of 1 to 3; each R1 and R2 is independently an alkyl group, an alkenyl group, an alkynyl group, an aryl group or a heterocyclic group, and X is a chlorine atom or a bromine atom, 
wherein Z2 is OR22, X2, or OH; n2 represents an integer of 1 to 3; each R21 and R22 is independently an alkyl group, an alkenyl group, an alkynyl group, an aryl group or a heterocyclic group, provided that R21 contains at least one primary amino group or at least two selected from the group consisting of primary and secondary amino groups; and X represents a chlorine atom or a bromine atom.
4. The photothermographic imaging material of item 3,
wherein the photosensitive silver halide has an average particle size of 0.03 to 0.10 xcexcm.
5. A photothermographic imaging material comprising a support having thereon a photosensitive layer comprising a photosensitive silver halide, a light-insensitive organic silver salt, a reducing agent for silver ions and a binder,
wherein the photosensitive layer comprises a compound represented by Formula (A) or Formula (B) and the photosensitive layer further comprises a compound represented by Formula (1): 
wherein each R3, R4 and R5 is independently an alkyl group, an alkenyl group, an alkynyl group, an aryl group or a heterocyclic group, provided that R5 includes a group represented by Formula (xcex1): 
wherein Z represents OR2, X, or OH; n is an integer of 1 to 3; each R1 and R2 is independently an alkyl group, an alkenyl group, an alkynyl group, an aryl group or a heterocyclic group; and X is a chlorine atom or a bromine atom, 
wherein Z2 represents OR22, X2, or OH; n2 is an integer of 1 to 3; each R21 and R22 is independently an alkyl group, an alkenyl group, an alkynyl group, an aryl group or a heterocyclic group, provided that R21 contains at least one primary amino group or at least two selected from the group consisting of primary and secondary amino groups; and X is a chlorine atom or a bromine atom 
wherein Q represents an aryl group or an aromatic heterocyclic group; T represents a single bond or a bivalent aliphatic linking group; J represents a linking group containing at least one of O, S, and N; each Ra, Rb, Rc and Rd independently represents H, an acyl group, an aliphatic group, an aryl group or a heterocyclic group, provided that Ra and Rb, Rc and Rd, Ra and Rc, or Rb and Rd may combine to form a nitrogen containing heterocyclic group; M is an ion; and k is an integer necessary to neutralize a charge.
6. The photothermographic imaging material of item 1,
wherein Z in Formula (B) represents OR21, R21 containing at least two selected from the group consisting of primary and secondary amino groups.
7. An image recording method, comprising a step of:
exposing the photothermographic imaging material of item 1 with a laser beam using a laser scanning exposure apparatus, wherein the photothermographic imaging material is exposed not substantially vertical to a surface of the photothermographic imaging material.
8. An image recording method, comprising a step of:
exposing the photothermographic imaging material of item 1 with a laser beam using a laser scanning exposure apparatus, wherein the photothermographic imaging material is exposed using a longitudinal multiple scanning method.
9. An image recording method, comprising a step of:
exposing the photothermographic imaging material of item 1 with a laser beam using a laser scanning exposure apparatus, wherein the photothermographic imaging material is exposed not substantially vertical to a surface of the photothermographic imaging material using a longitudinal multiple scanning method.
10. An image forming method, comprising the steps of:
(a) exposing the photothermographic imaging material of item 1 with a light using an exposure apparatus; and then
(b) subjecting the photothermographic imaging material to thermal development at a temperature of 80 to 200xc2x0 C.
11. An image forming method, comprising the steps of:
(a) exposing the photothermographic imaging material of item 1 with a laser beam using a laser scanning exposure apparatus; and then
(b) subjecting the photothermographic imaging material to thermal development at a temperature of 80 to 200xc2x0 C.
The present invention will now be detailed.
The silver salt photothermographic dry imaging materials of the present invention contain a compound represented by Formula (A) or Formula (B).
A compound represented by Formula (A) will be described.
In the group represented by Formula (xcex1), Z is OR2, X or OH, and xe2x80x9cnxe2x80x9d is an integer of 1 to 3, and X is a chlorine atom or a bromine atom.
In Formula (xcex1), each R1 and R2 is a straight-chained, branched or cyclic alkyl group of 1 to 30 carbon atoms (e.g., methyl, ethyl, butyl, octyl, dodecyl, cycloalkyl), an alkenyl group (e.g., propenyl, butenyl, nonenyl), an alkynyl group (e.g., ethynyl, bis-ethynyl, phenyl-ethynyl), an aryl group or a heterocyclic group (e.g., phenyl, naphtyl, tetrahydropyranyl, pyridyl, furyl, thienyl, imidazole, thiazole, thiadiazole, oxadiazole). These groups may further have a substituent of an electron-withdrawing group or an electron-donating group.
Examples of said substituents are an alkyl group of 1 to 25 carbon atoms (e.g., methyl, ethyl, propyl, isopropyl, tert-butyl, pentyl, hexyl, cyclohexyl), a halogenated alkyl group (e.g., trifluoromethyl, perfluorooctyl), a cycloalkyl group (e.g., cyclohexyl, cyclopentyl), an alkynyl group (e.g., propynyl), a glycidyl group, an acrylate group, a methacrylate group, an aryl group (e.g., phenyl), a heterocyclic group (e.g., pyridyl, thiazolyl, oxazolyl, imidazolyl, furyl, pyrrolyl, pyrazinyl, pyrimidinyl, selenazolyl, sulfolanyl, piperidinyl, pyrazolyl, tetrazolyl), a halide atom (e.g., chlorine, bromine, iodine, fluorine), an alkoxy group (e.g., methoxy, ethoxy, propoxy, cyclopentyloxy, hexyloxy, cyclohexyloxy), an aryloxy group (e.g., phenoxy), an alkoxycarbonyl group (e.g., methoxycarbonyl, ethoxycarbonyl, butoxycarbonyl), an aryloxycarbonyl group (e.g., phenoxycarbonyl), a sulfonamide group (e.g., methanesufonamide, ethanesulfonamide, butanesulfonamide, hexanesulfonamide, cyclohexanesulfonamide, benzenesulfonamide), a sulfamoyl group (e.g., aminosulfonyl, methylaminosulfonyl, dimethylaminosulfonyl, butylaminosulfonyl, hexylaminosulfonyl, cyclohexylaminosulfonyl, phenylaminosulfonyl, 2-pyridylaminosulfonyl), a ureido group (e.g., methylureide, ethylureide, pentylureide, cyclohexylureide, phenylureide, 2-pyridylueide), an acyl group (e.g., acetyl, propionyl, butanoyl, hexanoyl, cyclohexanoyl, benzoyl, pyridinoyl), a carbamoyl group (e.g., aminocarbonyl, methylaminocarbonyl, dimethylaminocarbonyl, propylaminocarbonyl, pentylaminocarbonyl, cyclohexylaminocarbonyl, phenylaminocarbonyl, 2-pyridylaminocarbonyl), an amido group (e.g., acetamide, propionamide, butanamide, hexanamide, benzamide), a sulfonyl group (e.g., methysulfonyl, ethylsulfonyl, butylsulfonyl, cyclohexylsulfonyl, phenylsulfonyl, 2-pyridylsulfonyl), an amino group (e.g., amino, ethylamino, dimethylamino, butylamino, cyclopentylamino, anilino, 2-pyridylamino), a cyano group, a nitro group, a sulfo group, a carboxyl group, a hydroxyl group, or an oxamoyl group. Each of these groups may further be substituted with other substituents described above.
Particularly, R1 and R2 are preferably an unsubstituted alkyl group having 1 to 3 carbon atoms.
A plurality of the substituents represented by Formula (xcex1) may exist in one molecule of a compound represented by Formula (A), but only one substituent is preferred.
Examples of groups represented by R3, R4 and R5 in Formula (A) are the same as defined for the above described R1 and R2 in Formula (xcex1). In particular, R5 contains a group represented by Formula (xcex1). Further, R3 and R4 may combine with each other to form a ring structure.
A compound represented by Formula (B) of the present invention will be described.
In Formula (B), Z2 is OR22, X2, or OH; n2 is an integer of 1 to 3; each R21 and R22 is independently an alkyl group, an alkenyl group, an alkynyl group, an aryl group or a heterocyclic group, provided that R21 contains at least one primary amino group or at least two selected from the group consisting of primary and secondary amino groups; and X is a chlorine atom or a bromine atom.
R21 preferably contains at least two amino groups selected from the group consisting of primary and secondary amino groups.
In Formula (B), R21 may combine with another R21 to form a structure having a plurality of Sixe2x80x94Z2n2.
An alkyl group, an alkenyl group, an alkynyl group, an aryl group or a heterocyclic group used for R21 and R22 in the Formula (B) will be described.
In Formula (B), each R1 and R2 is a straight-chained, branched or cyclic alkyl group of 1 to 30 carbon atoms (e.g., methyl, ethyl, butyl, octyl, dodecyl, cycloalkyl), an alkenyl group (e.g., propenyl, butenyl, nonenyl), an alkynyl group (e.g., ethynyl, bis-ethynyl, phenyl-ethynyl), and an aryl group or the heterocyclic group (e.g., phenyl, naphtyl, tetrahydropyranyl, pyridyl, furyl, thienyl, imidazolyl, thiazolyl, thiadiazolyl, oxadiazolyl). These groups may further have a substituent of an electron-withdrawing group or an electron-donating group.
Examples of said substituents are an alkyl group of 1 to 25 carbon atoms (e.g., methyl, ethyl, propyl, isopropyl, tert-butyl, pentyl, hexyl, cyclohexyl), a halogenated alkyl group (e.g., trifluoromethyl, perfluorooctyl), a cycloalkyl group (e.g., cyclohexyl, cyclopentyl), an alkynyl group (e.g., propynyl), a glycidyl group, an acrylate group, a methacrylate group, an aryl group (e.g., phenyl), a heterocyclic group (e.g., pyridyl, thiazolyl, oxazolyl, imidazolyl, furyl, pyrrolyl, pyrazinyl, pyrimidinyl, selenazolyl, sulfolanyl, piperidinyl, pyrazolyl, tetrazolyl), a halide atom (e.g., chlorine, bromine, iodine, fluorine), an alkoxy group (e.g., methoxy, ethoxy, propoxy, cyclopentyloxy, hexyloxy, cyclohexyloxy),an aryloxy group (e.g., phenoxy), an alkoxycarbonyl group (e.g., methyloxycarbonyl, ethyloxycarbonyl, butyloxycarbonyl), an aryloxycarbonyl group (e.g., phenyloxycarbonyl), a sulfonamide group (e.g., methanesufonamide, ethanesulfonamide, butanesulfonamide, hexanesulfonamide, cyclohexanesulfonamide, benzenesulfonamide), a sulfamoyl group (e.g., aminosulfonyl, methylaminosulfonyl, dimethylaminosulfonyl, butylaminosulfonyl, hexylaminosulfonyl, cyclohexylaminosulfonyl, phenylaminosulfonyl, 2-pyridylaminosulfonyl), a urethane group (e.g., methylureide, ethylureide, pentylureide, cyclohexylureide, phenylureide, 2-pyridylueide), an acyl group (e.g., acetyl, propionyl, butanoyl, hexanoyl, cyclohexanoyl, benzoyl, pyridinoyl), a carbamoyl group (e.g., aminocarbonyl, methylaminocarbonyl, dimethylaminocarbonyl, propylaminocarbonyl, pentylaminocarbonyl, cyclohexylaminocarbonyl, phenylaminocarbonyl, 2-pyridylaminocarbonyl), an amido group (e.g., acetamide, propionamide, buthanamide, hexanamide, benzamide), a sulfonyl group (e.g., methysulfonyl, ethylsulfonyl, butylsulfonyl, cyclohexylsulfonyl, phenylsulfonyl, 2-pyridylsulfonyl), an amino group (e.g., amino, ethylamino, dimethylamino, butylamino, cyclopentylamino, anilino, 2-pyridylamino), a cyano group, a nitro group, a sulfo group, a carboxyl group, a hydroxyl group, or an oxamoyl group. Each of these groups may further be substituted with other substituents described above.
Among these, R21 is preferably an alkyl group of 1 to 6 carbon atoms that contains at least one primary amino group or at least two primary or secondary amino groups. xe2x80x9cAt least two selected from the group consisting of primary and secondary amino groupsxe2x80x9d includes the following cases:
(i) at least one primary amino group and one secondary amino group;
(ii) at least two primary amino groups; and
(iii) at least two secondary amino groups.
In all of these cases, at least two amino groups are contained.
R22 is preferably an unsubstituted alkyl group having 1 to 3 carbon atoms.
A primary amino group and a secondary amino group that are contained in R21 will be described below.
Said primary or secondary amino group of the present invention includes amide, urethane, urea, thiourea, sulfonamide or hydrazine, in addition to an amino group. Further, said amino group may be substituted. Examples of substituents onto said amino group are the same substituents as defined for the above R1 and R2 in Formula (xcex1). Furthermore, secondary amino groups may combine with each other to form a ring structure.
A compound represented by Formula (A), or a compound represented by Formula (B) may be employed as a salt of hydrochloric acid or sulfuric acid.
Listed as examples of compounds of the present invention, represented by Formula (A), or by Formula (B) (hereinafter, merely referred to also as silyl compounds of the present invention), are shown below, but the present invention is not limited to these examples. 
The above-mentioned compounds can be synthesized in accordance with a method employing an alkoxy silane or a silyl halide as starting raw materials and combining them with a linking group. Further, hydroxy silyl compound can be obtained by adding water of an amount of more than the chemical equivalent volume to an alkoxy silane or a silyl halide.
In the present invention, the addition of said silyl compound is carried out in accordance with conventionally known methods. For example, a silyl compound may be added after having been dissolved in a polar solvent such as alcohols (e.g., methanol and ethanol), ketones (e.g., methyl ethyl ketone and acetone), dimethyl sulfoxide or dimethylformamide. Hydroxy silyl compounds may be added as an aqueous solution. Further, silyl compounds may be added as dispersed fine particles in water or organic solvent. The dispersion can be carried out by employing a disperser such as a sand mill, a jet mill, an ultra-sonic disperser or a homogenizer, to obtain an average particle diameter of at most 1 xcexcm. Furthermore, used may be any dispersion methods employing a sand mill disperser using glass beads or fine zirconia particle media, shattering the silyl compound solution by ejecting it at a high speed from a narrow tube onto a hard plate, or making silyl compound solution collide with each other in two directions from the narrow tube. The fine particle dispersion has preferably an average particle diameter of not less than 1 nm and not more than 10 xcexcm in an aqueous solution, and also preferably a narrow distribution of dispersed particles. When said silyl compound is dispersed into an aqueous solution, an aqueous solvent generating minimal foam during string is preferred. Regarding fine particle dispersing techniques, many techniques are conventionally disclosed, and the dispersion of the present invention may be carried out in accordance with the optimal technique.
In order to obtain a high density image of the present invention, the use of a compound represented by Formula (B) is preferable. Further, R21 is preferably an alkyl group, an alkenyl group, an alkynyl group, an aryl group or a heterocyclic group, provided that R21 contains at least one primary amino group or at least two primary or secondary amino groups. And Z2 is preferably a group represented by OR22.
A silyl compound of the present invention may be added into the layer containing additives such as a silver halide, an organic silver salt or a reducing agent, or into the layer adjacent to the above additive containing layer, or into an intermediate layer. The amount of said silyl compound of the present invention is preferably 1xc3x9710xe2x88x928 to 1.0 mol per 1 mol of silver, especially preferred is, 1xc3x9710xe2x88x925 to 1xc3x9710xe2x88x921 mol. Said amount of silyl compound may be decided by calculation of converting it into a unit area, when added to a layer other than a sensitized layer which does not contain silver. Increased fog and lowered maximum density may be caused by too much of said added amount, and an insufficient effect of the present invention may be obtained by too little of said added amount.
The amount of a silver coverage of the present invention can be measured by a known analytical method. For example, silver salt photothermographic dry imaging material is cut to a suitable size, and the cut film is set into X-ray fluorescence analysis system model 3080 (manufactured by Rigaku Denki Kougyou Corp.). Thus, the silver coverage can be calculated by measuring X-ray intensity of the objective element.
The silver coverage of the present invention is preferably at least 0.8 g/m2 and at most 2.5 g/m2. More preferably the silver coverage is from 0.8 to 1.6 g/m2. When the silver coverage is less than 0.8 g/m2, sufficient sensitivity or maximum density may not be obtained. And, when the silver coverage is more than 2.5 g/m2, an increase of fog may result.
The light sensitive silver halide, contained in the light sensitive layer of the silver salt photothermographic dry imaging material, used in the present invention can be prepared by using any of the several methods known in the field of the photographic industry, of single-jet or double-jet addition, and any one of an ammonia precipitation, a neutral precipitation and an acidic precipitation. A silver halide functions as a photo-sensor. In order to minimize cloudiness or white turbidness after image formation and to obtain excellent image quality, the size of silver halide grains are preferably smaller than that used in a wet processing silver halide photographic material. The average grain size is preferably 0.01 xcexcm to 0.15 xcexcm, and more preferably 0.03 xcexcm to 0.10 xcexcm. If less than 0.01 xcexcm, sufficient sensitivity or maximum densities may not be obtained. Further, if exceeding 0.15 xcexcm, sufficient maximum densities may not be obtained or high fog densities may result.
The silver halide grain shape is not specifically limited, and can be any one of several shapes, including so-called regular crystals in the form of a cube or an octahedron but not regular crystals of spherical, cylindrical and tabular grains. Further, the composition of silver halide grains is not limited and may be any one of silver chloride, silver chlorobromide, silver iodochlorobromide, silver bromide, silver iodobromide or silver iodide.
The silver halide grains of the present invention can be prepared by converting a part or all of an organic silver salt to silver halide by employing a silver halide forming component. Examples of such silver halide forming components are; inorganic halides, onium halides, halogenated hydrocarbons and other halides. These are detailed in U.S. Pat. Nos. 4,009,039, 3,457,075 and 4,003,749, British Pat. No. 1,498,956, Japanese Patent Publication Open to Public Inspection (hereinafter referred to as JP-A) Nos. 53-27027 and 53-25420. The conditions of the production process of conversion to silver halide such as reaction time, reaction temperature and reaction pressure are appropriately set up according to the objective of silver halide preparation, and a generally preferable set-up is a reaction temperature of xe2x88x9223xc2x0 C. to 74xc2x0 C., a reaction time of 0.1 second to 72 hours and a reaction pressure of atmospheric pressure.
The light sensitive silver halide prepared by various of the above-mentioned methods may be chemically sensitized by, for example, a sulfur containing compound, a gold compound, a platinum compound, a palladium compound, a silver compound, a tin compound, a chromium compound and a combination of these compounds. A method and a procedure of said chemical sensitization are described in such as U.S. Pat. No. 4,036,650, British Patent No. 1,518,850, JP-A Nos. 51-22430, 51-78319 and 51-81124.
The silver halide used in the present invention may be sensitized by a spectral sensitizing dye, if required. The sensitizing dyes described in the following references can be employed: JP-A Nos. 63-159841, 60-140335, 63-231437, 63-259651, 63-304242 and 63-15245, and U.S. Pat. Nos. 4,639,414, 4,740,455, 4,741,966, 4,751,175 and 4,835,096. Particularly, the sensitizing dyes having a spectral sensitivity suitable for spectral characteristics of light sources of various types of scanners can advantageously be selected. For example, dyes are preferably selected from compounds described in JP-A Nos. 9-34078, 9-54409 and 9-80679.
The compound represented by Formula (1) will now be explained.
In the present invention, the compound represented by Formula (1) and a macrocyclic compound (both are disclosed in JP-A No. 2001-330918) may be employed as a supersensitizer.
In the above-mentioned Formula (1), the bivalent aliphatic hydrocarbon linking group, represented by T includes a straight-chain, a branched or a cyclic alkylene group (preferably having 1 to 20 carbon atoms, more preferably 1 to 16, and still more preferably 1 to 12), an alkenyl group (preferably having 2 to 20 carbon atoms, more preferably 2 to 16 carbon atoms, and still more preferably 2 to 12 carbon atoms), an alkynyl group (preferably having 2 to 20 carbon atoms, more preferably 2 to 16 carbon atoms, and still more preferably 2 to 12 carbon atoms), each of which may be substituted by substituent group(s). The substituent groups are; an aliphatic hydrocarbon groups, for example, an alkyl group (preferably having 1 to 20 carbon atoms, more preferably 1 to 16 carbon atoms, and still more preferably 1 to 12 carbon atoms), an alkenyl group (preferably having 2 to 20 carbon atoms, more preferably 2 to 16 carbon atoms, and still more preferably 2 to 12 carbon atoms), an alkynyl group (preferably having 2 to 20 carbon atoms, more preferably 2 to 16 carbon atoms, and still more preferably 2 to 12 carbon atoms), a monocyclic or condensed cyclic aryl group having 6 to 20 carbon atoms (e.g., phenyl or naphthyl but preferably phenyl), and a saturated or unsaturated heterocyclic group having 3 to 10 members (e.g., 2-thiazolyl, 1-piperazinyl, 2-pyridyl, 3-pyridyl, 2-furyl, 2-thienyl, 2-benzimidazolyl, carbazolyl). The heterocyclic group may be a monocyclic ring or a ring condensed with other rings. These groups each may further be substituted at any position. Examples of such substituent groups include an alkyl group (including a cycloalkyl group and an aralkyl group, and preferably having 1 to 20 carbon atoms, more preferably 1 to 12 carbon atoms, and still more preferably 1 to 8 carbon atoms, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, tert-butyl, n-heptyl, n-octyl, n-decyl, n-undecyl, n-hexadecyl, cyclopropyl, cyclopentyl, cyclohexyl, benzyl, or phenethyl), an alkenyl group (preferably having 2 to 20 carbon atoms, more preferably 2 to 12 carbon atoms, and still more preferably 2 to 8 carbon atoms, e.g., vinyl, allyl, 2-butenyl, or 3-pentenyl), an alkynyl group (preferably having 2 to 20 carbon atoms, more preferably 2 to 12 carbon atoms, and still more preferably 2 to 8 carbon atoms, e.g., propynyl, or 3-pentynyl), an aryl group (preferably having 6 to 30 carbon atoms, more preferably 6 to 20 carbon atoms, and still more preferably 6 to 12 carbon atoms, e.g., phenyl, p-tolyl, o-aminophenyl, or naphthyl), an amino group (preferably having 0 to 20 carbon atoms, more preferably 0 to 10 carbon atoms, and still more preferably 0 to 6 carbon atoms, e.g., amino, methylamino, ethylamino, dimethylamino, diethylamino, diphenylamino, or dibenzylamino), an imino group (preferably having 1 to 20 carbon atoms, more preferably 1 to 18 carbon atoms, and still more preferably 1 to 12 carbon atoms, e.g., methylimino, ethylimino, propylimino, or phenylimino), an alkoxy group (preferably having 1 to 20 carbon atoms, more preferably 1 to 12 carbon atoms, and still more preferably 1 to 8 carbon atoms, e.g., methoxy, ethoxy, ethoxy, or butoxy), an aryloxy group (preferably having 6 to 20 carbon atoms, more preferably 6 to 16 carbon atoms, still more preferably 6 to 12 carbon atoms, e.g., phenoxy, or 2-naphthyloxy), an acyl group (preferably having 1 to 20 carbon atoms, more preferably 1 to 16 carbon atoms, and still more preferably 1 to 12 carbon atoms, e.g., acetyl, benzoyl, formyl, or pivaloyl), an alkoxycarbonyl group (preferably having 2 to 20 carbon atoms, more preferably 2 to 16 carbon atoms, and still more preferably 2 to 12 carbon atoms, e.g., methoxycarbonyl or ethoxycarbonyl), an aryloxycarbonyl group (preferably having 7 to 20 carbon atoms, more preferably 7 to 16 carbon atoms, and still more preferably 7 to 10 carbon atoms, e.g., phenoxycarbonyl), an acyloxy group (preferably having 1 to 20 carbon atoms, more preferably 1 to 16 carbon atoms, and still more preferably 1 to 10 carbon atoms, e.g., acetoxy, benzoyloxy), an acylamino group (preferably having 1 to 20 carbon atoms, more preferably 1 to 16 carbon atoms, and still more preferably 1 to 10 carbon atoms, e.g., acetylamino or benzoylamino), alkoxycarbonylamino group (preferably having 2 to 20 carbon atoms, more preferably 2 to 16 carbon atoms, and still more preferably 2 to 12 carbon atoms, e.g., methoxycarbonylamino), aryloxycarbonylamino group (preferably having 7 to 20 carbon atoms, more preferably 7 to 16 carbon atoms, and still more preferably 7 to 12 carbon atoms, e.g., phenoxycarbonylamino), a sulfonylamino group (preferably having 1 to 20 carbon atoms, more preferably 1 to 16 carbon atoms, and still more preferably 1 to 12 carbon atoms, e.g., methanesulfonylamino or benzenesulfonylamino), a sulfamoyl group (preferably having 0 to 20 carbon atoms, more preferably 0 to 16 carbon atoms, and still more preferably 0 to 12 carbon atoms, e.g., sulfamoyl, methylsulfamoyl, dimethylsulfamoyl, or phenylsulfamoyl), a carbamoyl group (preferably having 1 to 20 carbon atoms, more preferably 1 to 16 carbon atoms, and still more preferably 1 to 12 carbon atoms, e.g., carbamoyl, methycarbamoyl, or diethylcarbamoyl, phenylcarbamoyl), an alkylthio group (preferably having 1 to 20 carbon atoms, more preferably 1 to 16 carbon atoms, and still more preferably 1 to 12 carbon atoms, e.g., methylthio or ethylthio), an arylthio group (preferably having 6 to 20 carbon atoms, more preferably 6 to 16 carbon atoms, and still more preferably 6 to 12 carbon atoms, e.g., phenylthio), a sulfonyl group (preferably having 1 to 20 carbon atoms, more preferably 1 to 16 carbon atoms, and still more preferably 1 to 12 carbon atoms, e.g., methanesulfonyl or tosyl), a sulfinyl group (preferably having 1 to 20 carbon atoms, more preferably 1 to 16 carbon atoms, and still more preferably 1 to 12 carbon atoms, e.g., methanesulfinyl or benzenesulfinyl), an ureido group (preferably having 1 to 20 carbon atoms, more preferably 1 to 16 carbon atoms, and still more preferably 1 to 12 carbon atoms, e.g., ureido, methylureido, or phenylureido), a phosphoric amide group (preferably having 1 to 20 carbon atoms, more preferably 1 to 16 carbon atoms, and still more preferably 1 to 12 carbon atoms, e.g., diethylphosphoric acid amide or phenylphosphoric acid amide), a hydroxy group, a mercapto group, a halogen atom (e.g., fluorine atom, chlorine atom, bromine atom, or iodine atom), a cyano group, a sulfo group, a sulfino group, a carboxyl group, a phosphono group, a phosphino group, a nitro group, a hydroxamic acid group, a hydrazine group, and a heterocyclic group (e.g., imidazolyl, benzimidazolyl, thiazolyl, benzothiazolyl, carbazolyl, pyridyl, furyl, piperidinyl, or morpholinyl).
Of the substituent groups described above, a hydroxy group, a mercapto group, a sulfo group, a sulfino group, a carbokyl group, a phosphono group, and a phosphino group include their salts. These substituent groups may be further substituted. In this case, plural substituents may be the same or different.
The preferred substituent groups include an alkyl group, an aralkyl group, an alkoxy group, an aryl group, an alkylthio group, an acyl group, an acylamino group, an imino group, a sulfamoyl group, a sulfonyl group, a sulfonylamino group, a ureido group, an amino group, a halogen atom, a nitro group, a heterocyclic group, an alkoxycarbonyl group, a hydroxy group, a sulfo group, a carbamoyl group, and a carboxyl group. Specifically, an alkyl group, an alkoxy group, an aryl group, an alkylthio group, an acyl group, an acylamino group, an imino group, a sulfonylamino group, a ureido group, an amino group, a halogen atom, a nitro group, a heterocyclic group, an alkoxycarbonyl group, a hydroxy group, a sulfo group, a carbamoyl group, and a carboxyl group are more preferred; and an alkyl group, an alkoxy group, an aryl group, an alkylthio group, an acylamino group, an imino group, a ureido group, an amino group, a heterocyclic group, an alkoxycarbonyl group, a hydroxy group, a sulfo group, a carbamoyl group, and a carboxyl group are still more preferred. An amidino group having a substituent or without a substituent is also preferable. Examples of the substituents on the amidino group include an alkyl group (e.g., methyl, ethyl, pyridylmethyl, benzyl, phenethyl, carboxybenzyl, and aminophenylmethyl), an aryl group (e.g., phenyl, p-tolyl, naphthyl, o-aminophenyl, and o-methoxyphenyl), and a heterocyclic group (e.g., 2-thyazolyl, 2-pyridyl, 3-pyridyl, 2-furyl, 3-furyl, 2-thieno, 2-imidazolyl, benzothiazolyl, and carbazolyl).
Examples of bivalent linking groups represented by J that contains at least one of an oxygen atom, a sulfur atom or a nitrogen atom are listed as follows. These linking groups may combine with each other. 
Wherein, Re and Rf are the same as defined for Ra through Rd.
An aromatic hydrocarbon group represented by Q is a monocyclic or condensed aryl group (preferably having 6 to 30 carbon atoms, and more preferably 6 to 20 carbon atoms).
Examples of these include phenyl and naphthyl, and phenyl is preferred. An aromatic heterocyclic group represented by Q is a 5- to 10-membered unsaturated heterocyclic group containing at least either N, O or S, and may be monocyclic or condensed with other rings. A heterocyclic ring of the heterocyclic group is preferably a 5- or 6-membered aromatic heterocyclic ring or its benzo-condensed ring, more preferably a nitrogen-containing, 5- or 6-membered aromatic heterocyclic ring or its benzo-condensed ring, and still more preferably one or two nitrogen-containing, 5- or 6-membered aromatic heterocyclic ring or its benzo-condensed ring.
Examples of the aromatic heterocyclic groups include groups derived from thiophene, furan, pyrrole, imidazole, pyrazole, pyridine, pyrazine, pyridazine, triazole, triazine, indole, indazole, purine, thiadiazole, oxadiazole, quinoline, phthalazine, naphthylizine, quinoxaline, quinazoline, cinnoline, pteridine, acridine, phenanthroline, phenazine, tetrazole, thiazole, oxazole, benzimidazole, benzoxazole, benzothiazole, benzothiazoline, benzotriazole, tetrazaindene, and carbazole. Of these, groups derived from imidazole, pyrazole, pyridine, pyrazine, indole, indazole, thiadiazole, oxadiazole, quinoline, phenazine, tetrazole, thiazole, oxazole, benzimidazole, benzoxazole, benzothiazole, benzothiazoline, benzotriazole, tetrazaindene, and carbazole are preferred; and groups derived from imidazole, pyridine, pyrazine, quinoline, phenazine, tetrazole, thiazole, benzoxazole, benzimidazole, benzothiazole, benzothiazoline, benzotriazole, and carbazole are more preferred.
An aromatic hydrocarbon groups and aromatic heterocyclic groups represented by Q may be substituted. The substituent groups are the same as the substituent groups defined for T, and the preferable range is also the same. The substituent groups may be further substituted. When there are a plurality of substituents, they may be the same or different. Further, the group represented by Q is preferably an aromatic heterocyclic group.
An aliphatic hydrocarbon group, aryl group and heterocyclic group, represented by Ra, Rb, Rc, and Rd, are the same as the groups of examples of an aliphatic hydrocarbon group, aryl group and heterocyclic group for the above-mentioned T. The preferable range is also the same. An acyl group represented by Ra, Rb, Rc and Rd includes an aliphatic or aromatic group, having 1 to 12 carbon atoms, such as acetyl, benzoyl, formyl and pivaloyl. A nitrogen containing heterocyclic group formed by combinations of Ra and Rb, Rc and Rd, Ra and Rc, or Rb and Rd includes a 3- to 10-membered, saturated or unsaturated heterocyclic ring (e.g., ring groups such as piperidine ring, piperadine ring, acridine ring, pyrrolidine ring, pyrrole ring, or morpholine ring).
Examples of acid anions represented by M and used for neutralizing a molecular charge are; a halide ion (e.g., chloride ion, bromide ion, and iodide ion), a p-toluenesulfonate ion, a perchlorate ion, a tetrafluoroborate ion, a sulfate ion, a methylsulfate ion, an ethylsulfate ion, a methanesulfonic acid ion and a trifluoromethanesulfonic acid ion.
Examples of compounds represented by Formula (1) are shown below but the present invention are not limited to these examples. 
The compound (supersensitizer) of the present invention, represented by Formula (1) is employed in an emulsion layer containing organic silver salt and silver halide grains in an amount of preferably 0.001 to 1.0 mol per 1 mol of silver. Especially the preferable amount of the compound is 0.01 to 0.5 mol per mol of silver.
Organic silver salts used in the present invention of silver salt photothermographic dry imaging material are silver sources capable to be reduced. Silver salts of organic acids, hetero organic acids and polymer acids are employed. Specifically, organic or inorganic silver complexes, ligands of which having a total stability constant to a silver ion of 4.0 to 10.0 are preferred. Preferred organic acids employed to prepare a preferable organic silver salt are such as gallic acid, oxalic acid, behenic acid, stearic acid, palmitic acid and lauric acid. The organic silver salts can be prepared by mixing an alkali metal salt of the above-mentioned organic acid and silver nitrate. Both solutions may be mixed by a controlled double jet method or either one the solutions may be added by shifting the timing of addition of each component. One of the solutions may be portioned and added in several times or at one time of a selected time during formation of silver salts.
The suitable examples of the reducing agents to be included in the silver salt photothermographic dry imaging material of the invention are suitably selected from reducing agents well known in the art. Such reducing agents are; polyphenols in which two or more phenol groups are bonded by an alkylene group or sulfur, and particularly polyphenols in which at least one position of adjacent to hydroxy substituted positions being substituted by an alkyl group (such as a methyl group, an ethyl group, a propyl group, a t-butyl group and an cyclohexyl group) or an acyl group (such as an acetyl group and a propionyl group), are bonded by an alkylene group or sulfur. Examples of such compounds are as follows:
(Re1) 1,1-bis(2-hydroxy-3, 5-dimethylphenyl)-3, 5, 5-trimethylhexane
(Re2) 1,1-bis(2-hydroxy-3-t-butyl-5-methylphenyl)methane
(Re3) 1,1-bis(2-hydroxy-3, 5-di-t-butylphenyl)methane
(Re4) 1,1-bis(2-hydroxy-3-methyl-5-t-butylphenyl)methane
(Re5) 1,1-bis[2-hydroxy-3-methyl-5-(1-methylcyclohexyl)phenyl]methane
(Re6) (2-hyrdoxy-3-t-butyl-5-methylphenyl)-(2-hyrdoxy-5-methylphenyl)methane
(Re7) 6, 6xe2x80x2-benzylidene-bis(2,4-di-t-butylphenol)
(Re8) 6, 6xe2x80x2-benzylidene-bis(2-t-butyl-4-methylphenol)
(Re9) 6, 6xe2x80x2-benzylidene-bis(2,4-dimethylphenol)
(Re10) 1, 1-bis(2-hydroxy-3, 5-dimethylphenyl)-2-methylpropane
(Re11) 1, 1-bis(2-hydroxy-3, 5-dimethylphenyl)-1-cyclohexylmethane
(Re12) 1, 1-bis(2-hydroxy-3, 5-dimethylphenyl)-1-(2, 4-dimethyl-3-cyclohexenyl)methane
(Re13) 1, 1-bis(2-hydroxy-3, 5-dimethylphenyl)-1-(2-methyl-4-cyclohexenyl)methane
(Re14) 1, 1-bis(2-hydroxy-3, 5-dimethylphenyl)-1-(2-methyl-4-cyclohexyl)methane
(Re15) 1, 1-bis(2-hydroxy-3-methyl-5-t-butylphenyl)propane
(Re16) 1, 1-bis(2-hydroxy-3-methyl-5-t-butylphenyl)butane
(Re17) 1, 1, 5, 5-tetrakis-(2-hydroxy-3, 5-dimethylphenyl)-2, 4-ethylpentane
(Re18) 2, 2-bis(4-hydroxy-3, 5-dimethylphenyl)propane
(Re19) 2, 2-bis(4-hydroxy-3, 5-di-t-butylphenyl)propane.
Further, suitable examples also include polyphenol compounds described in the following references: U.S. Pat. Nos. 3,589,903, 4,021,249, British Patent No. 1,486,148, JP-A 51-51933, 50-36110, 50-116023, 52-84727, 2001-56527, 2001-42469, 2001-92075, 2001-188323, and JP-B 51-35727 (JP-B refers to an examined Japanese Patent Publication). Further examples are bisnaphtols described in U.S. Pat. No. 3,672,904 such as 2,2xe2x80x2-dihydroxy-1,1xe2x80x2-binaphtyl, 6,6xe2x80x2-dibromo-2,2xe2x80x2-dihydroxy-1,1xe2x80x2-binaphtyl, 6, 6xe2x80x2-dinitro-2, 2xe2x80x2-dihydroxy-1, 1xe2x80x2-binaphtyl, bis(2-hydroxy-1-naphtyl)methane, and 4, 4xe2x80x2-dimethoxy-1, 1xe2x80x2-dihydroxy-2, 2xe2x80x2-binaphtyl. Further, examples are sulfonamido phenols or sulfonamido naphthols described in U.S. Pat. No. 3,801,321 such as 4-benzenesulfonamido phenol, 2-benzenesulfonamido phenol, 2,6-dichloro-4-benzenesulfonamido phenol and 4-benzenesulfonamido naphthol.
Polymer binders employed in a light sensitive layer or in a non light sensitive layer of the photothermographic imaging material of the present invention include; polyacrylamide, polystyrene, polyvinyl acetate, polyurethane, polyacrylic acid ester, styrene-butadiene copolymer, acrylonitrile-butadiene copolymer, vinyl chloride-vinyl acetate-copolymer, and styrene-butadiene-acryl copolymer. Further preferred binders are these having low equilibrium moisture content after being coated and dried to form a film. Especially low moisture content binders are, for example, such as cellulose acetate, cellulose acetate butylate, cellulose acetate propionate and polyvinylacetal used in an organic solvent.
Polyvinylacetal can be synthesized by acetalization of polyvinylalcohol with an aldehyde such as butylaldehyde or acetaldehyde.
The degree of acetalization is theoretically 1 to 100%, but preferably 20 to 95% for practical use. A low degree of acetalization increases hydroxyl groups and results in showing low resistance to humidity of photographic properties, and a high degree of acetalization requires a higher reaction temperature and a longer reaction time, and results in increased cost and lowered productivity.
The degree of polymerization of polyvinylalcohol used as a starting material is selected from about 10 to about 100,000, but 100 to 6,000 is preferable from the view point of coating characteristics and productivity of synthesis.
When forming a layer with binders alone, adhesion to the under layer and the upper layer can be maintained and layer strength that will not be easily damaged can be obtained. Further, the usage of a cross linking agent is effective to obtain higher layer adhesion and layer strength.
Examples of the cross linking agents of the present invention are listed below. When the cross linking reaction is slow, the photographic properties may not be stable and the storage stability may be deteriorated. The cross linking agents employed in the present invention may be preferably selected from multifunctional types having at least 2 isocyanate groups. The preferred cross linking agents are shown below:
(H1) hexamethylenediisocyanate
(H2) trimer of hexamethylenediisocyanate
(H3) tolyrendiisocyanate
(H4) phenylenediisocyanate
(H5) xylenediisocyanate
(H6) 1,3-bis (isocyanatemethyl) cyclohexane
(H7) tetramethylenexylilenediisocyanate
(H8) m-isopropenil-xcex1,xcex1-dimethylbenzylisocyanate 
The above-mentioned cross linking agents may be added by dissolving in water, alcohols, ketones or non-polar organic solvents, or added as a solid state to the coating composition. The adding amount of the cross linking agents is preferably equivalent to targeted cross linking groups, and may be increased up to 10 times in volume, and decreased to {fraction (1/100)} in volume. When too little volume is employed, the cross linking reaction may not proceed, and when too much volume is employed, an unreacted cross linking agent may deteriorate the photographic properties. Thus, both too little and too much amount are not preferred.
The silver salt photothermographic dry imaging material of the present invention comprises, if necessary, an AH (anti-halation)layer or a BC (back-coating) layer in order to obtain an anti-halation effect. The used dyes in said HC layer or BC layer may be any dyes that absorb the light used for image exposure, and preferable examples are described in JP-A H2-216140, H7-13295, H7-11432, and U.S. Pat. No. 5,380,635.
The supports of the present invention are preferably polyethylene terephthalate, polyethylene naphthalate, or syndiotactic polystyrene. The supports are preferably biaxially stretched and thermally fixed in order to obtain a high optical isotropic property and a high dimensional stability. The support thickness is preferably 50 to 400 xcexcm.
The exposure method of the image recording method of the present invention will now be described.
Exposure of the silver salt photothermographic dry imaging material of the present invention may desirably be an argon ion laser, a Hexe2x80x94Ne laser, a red semiconductor laser or a near-infrared semiconductor laser. The use of an infrared semiconductor laser is preferred because it has a high output power and it is possible to make the support of photothermographic dry imaging material transparent.
In the present invention, the use of a laser scanning exposure apparatus is preferred, in which the scanning light is exposed at an angle of not substantially vertical to the exposure surface of the silver salt photothermographic dry imaging material.
The expression xe2x80x9claser light is exposed at an angle of not substantially vertical to the exposure surface of the silver salt photothermographic dry imaging materialxe2x80x9d means that a laser light is exposed preferably at an angle of 55 to 88 degrees during laser scanning, more preferably 60 to 86 degrees, and still more preferably 65 to 84 degrees, and optimally 70 to 82 degrees.
When the silver salt photothermographic dry imaging material is scanned with a laser light, the beam spot diameter on the surface of the silver salt photothermographic dry imaging material is preferably not more than 200 xcexcm, and more preferably not more than 100 xcexcm. Because, the smaller spot diameter preferably reduces the angle displaced from verticality of the laser incident angle.
The lower limit of the beam spot diameter is 10 xcexcm. The above-mentioned laser scanning exposure can reduce deterioration in image quality caused by a reflected light, such as occurrence of interference fringe pattern unevenness.
Exposure applicable to the present invention is preferably conducted by using a laser scanning exposure apparatus that produces a longitudinal multiple scanning laser light. By using this laser light, deterioration in image quality such as occurrence of interference fringe pattern unevenness is reduced, as compared to scanning laser light with a longitudinally single mode.
A longitudinal multiple scanning can be achieved by a technique of composing waves, employing backing light or high frequency overlapping. The expression xe2x80x9clongitudinally multiplexe2x80x9d means that the exposure wavelength is not a single wavelength. The wavelength distribution is usually not less than 5 nm, and preferably not less than 10 nm. The upper limit of the exposure wavelength is not specifically limited but is usually about 60 nm.
Thermal development of the image forming method of the present invention will now be described.
The silver salt photothermographic dry imaging material of the present invention is stable at a normal temperature (20xc2x115xc2x0 C.). After exposure, said material is developed by heating to a higher temperature. The heating temperature is preferably 80 to 200xc2x0 C., and more preferably 100 to 150xc2x0 C. Sufficiently high image densities cannot be obtained at a temperature lower than 80xc2x0 C., and at a temperature higher than 200xc2x0 C., the binder melts and is transferred onto the rollers, and thus, adversely affecting not only image itself but also transportability or the thermal processor. An oxidation-reduction reaction between an organic silver salt (functioning as an oxidant) and a reducing agent is caused upon heating to form silver images. The reaction process proceeds without supplying any processing solution such as water from the exterior.
The present invention will be further described based on examples but embodiments of the present invention are by no means limited to these examples.